Tuesday, December 20, 2011

Nano-Engineered Bioconstructs Perform Photosynthesis Faster Than Nature Does | Popular Science: Researchers led by Carolyn Lubner at Penn State worked with a cyanobacterium called Synechococcus and another bacterium, Clostridium acetobutylicum. In nature, photosynthetic organisms use light-capturing enzymes nicknamed Photosystem I and II, which absorb light and excite electrons to a higher energy state. Another enzyme called FNR then uses these electrons to produce an energy-storage molecule. This molecule is used to make sugars to keep the organism alive, and that's your basic photosynthesis process.
Lubner et al replaced the FNR enzyme with a hydrogenase enzyme, which combines electrons with hydrogen ions to make molecular hydrogen (instead of a sugar-producing system). Then they used this enzyme to stitch together iron-based terminals of a Photosystem I enzyme from each of the bacteria. This stitch served as a molecular wire, easily and quickly transferring electrons. The researchers doped it with vitamin C, which served as the electron feedstock.
The result was a high-throughput hydrogen-producing system — electron flow was more than twice as high as the bacteria’s individual rates, the authors say.